Benzyl thiocarbamate sulfoxides are well known in the pesticide art for their excellent herbicidal activity. A full description of such compounds together with their preparation and method of use is found in U.S. Pat. No. 3,897,492.
Unfortunately, thiocarbamate sulfoxides tend to decompose. This has been found to occur while the compounds are placed in storage for extended periods of time, and tends to accelerate at elevated temperatures. In addition, contact with dry soil and even with the clay and mineral carriers used in common pesticide formulations has been found to induce decomposition and deactivation of the compounds. A study on the stability of these compounds is found in Gozzo et al., "On the Thermal and Chemical Stability of Carbamoyl Sulfoxides," The Journal of Chemistry and Industry, Mar. 1, 1975.
The literature reports various attempts to stabilize thiocarbamate sulfoxides by adding stabilizing agents: the use of crystalline carbamoyl sulfoxide/urea adducts is described in U.S. Pat. No. 4,008,071, the use of hindered phenols is described in U.S. Pat. No. 4,117,010, and the use of acetylenic compounds is described in U.S. Pat. No. 4,081,468.
It has now been discovered that improved stability can be achieved in a granular benzyl thiocarbamate sulfoxide composition without the use of added stabilizing agents.